a) Field of the Invention
The present invention relates to an apparatus for the rehabilitation and, optionally, measurement of the musculoskeletal performance of a human body.
b) Brief Description of the Prior Art
Numerous apparatus are presently available in the market, for use in the rehabilitation of "parts" of the body of a patient, such as his or her wrist, shoulder ankle, knee or back.
These apparatuses which can be of very different structures, usually incorporate strain gauges or similar devices that make them also useful for measuring the isometric and/or isokinetic musculoskeletal performance of the patient.
A first example of such an apparatus is the one sold by PNEUMEX, INC. of Edmonton, Alberta, under the tradename "The Pneumex rehabilitation cylinder". This apparatus comprises a pneumatic cylinder that can be attached at one end by a suction cup and an universal joint to any non porous surface, and at the other end to the foot, knee, arm or wrist of the patient. The piston head within the cylinder define two chambers that are connected by a pneumatic line incorporating two manually adjustable control valves allowing independent pressure on the in and out stroke. A pressure gauge is also provided to give readings on both the in and out stroke.
Another example of apparatus is the one sold by CYBEX, a division of LUMEX, INC., of Ronkonkoma, New York, under the tradename LIFTASK. This other apparatus along with other apparatuses sold by the same company under the tradename of the "Torso Rotation" and "Trunk Extension/Flexion" units, is designed to complete testing, rehabilitation and screening of the back of a patient.
It basically comprises a handle fixed to a rope wound onto a winch whose rotation may be controlled by a motor. It also comprises an electronic load cell and a velocity tranducer connected to a computer to determine both the instantaneous forces and the velocity of motion, where the patient is asked to pull up the handle with his or her arms alone (arm lifting strength test), his or her legs alone (leg lifting strength test), or his or her back (torso lifting strength test).
If the rope is locked in position by preventing the winch from rotating, isometric or "static" measurement of the body performance can be obtained. Depending on the length of the rope and/or the vertical position of the handle (when use is made of other apparatuses of this type further comprising a vertical post along which the winch may be adjusted), it is possible to simulate objects being lifted or moved at various heights. Moreover, the handle can be made removable and replaced by straps, tools, boxes and the like for custom-designed job simulation.
If the rope is allowed to unwind with a given resistance and/or at a given speed, isokinetic or "dynamic" measurements of the body performance can be achieved (dynamic lift strength, dynamic back extension strength, dynamic elbow flexion strength). Of course, the velocity of the movement to be performed can be set by proper adjustment of the motor controlling the winch to meet some motion-distance/time requirements of the simulated job.
Measurements obtained with such an apparatus can be correlated with theoretical values of the compression or torsion forces applied to an articulation, such as, for example, the compression force on the L.sub.5 /S.sub.1 disc of the spine, which values can be obtained by resolution of mathematical equations applying to the particular structure of the articulation being tested. Thus, it becomes possible to evaluate the performance of a patient and/or the difficulty of a given job and, as a result, determine whether carrying out this job falls within standards like those established by recognized organizations such as the National Institute for Occupational Safety and Health (NIOSH) which, by way of example, has established that predicted L.sub.5 /S.sub.1 compression values above 3400N be considered as potentially hazardous to some people, and values greater than 6400N as hazardous to everybody.
Other apparatuses are also known, wherein the patient or part of his or her body is rigidly fixed in a vice-like structure that is "articulated" in a single plane. This of course causes the patient to move and perform the required job within this single plane only.